Adaptive filter based anti-strong transient impact method for vortex flowmeter

The vortex flowmeter is widely used for fluid flow measurement in industrial pipelines. However, the industrial sites may have complex situations, when pipelines are exposed to high-intensity or high-frequency transient impacts, the interference energy will surpass that of the vortex signal, leading to measurement errors in frequency estimation methods relying on the maximum spectrum peak. To address this problem, a large number of output signals from vortex sensor are collected when the pipeline system is subjected to strong transient impacts, the characteristics of both the vortex flow signal and the transient impact interference output from the vortex sensor are analyzed. The vortex flow signal is an approximately single-frequency signal, and its amplitude-frequency characteristics are similar to those of a band-pass filter. Therefore, the concept of constructing an adaptive band-pass filter using the vortex flow signal is proposed. The farther the output mixed signal is from the onset of the impact, the more similar it is to the characteristics of the vortex flow signal. Based on this feature, a method of constructing an adaptive filter is proposed for the situation where the vortex flow signal is unknown during actual measurement. To meet the instrumentation demands for low-power and real-time, a frequency domain filtering method based on FFT is employed to swiftly implement the anti-strong transient impact interference algorithm based on adaptive filter. An anti-strong transient impact interference system is constructed based on a low-power microcontroller, then gas flow validation experiments with two different primary instruments are conducted, the system can correctly extract the frequency of vortex flow when the number of strong transient impacts does not exceed 5 times per second.